Defining Childhood Weight Status

BMI for Children and Teens

Child & Teen BMI Calculator

Body mass index (BMI) is commonly used to determine childhood weight status. BMI is calculated by dividing a person’s weight in kilograms by the square of height in meters. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age.

A child’s weight status is different from adult BMI categories. Children’s body composition varies as they age and varies between boys and girls. Therefore, BMI levels among children and teens need to be expressed relative to other children of the same age and sex.

For example, a 10-year-old boy of average height (56 inches) who weighs 102 pounds would have a BMI of 22.9 kg/m². This would place the boy in the 95^th percentile for BMI, and he would be considered as having obesity. This means that the child’s BMI is greater than the BMI of 95% of 10-year-old boys in the reference population.

CDC Growth Charts are commonly used to measure the size and growth patterns of children and teens in the United States. BMI-for-age weight status categories and the corresponding percentiles, based on expert committee recommendations, and are in the following table:

In children, BMI percentile cutoffs for obesity are intended to reliably define a level above which a child is more likely to have or be at risk of developing obesity-associated adverse health outcomes or diseases. For more information, see a resource guide assessing childhood obesityexternal icon.

BMI does not measure body fat directly, but BMI is correlated with more direct measures of body fat, such as skinfold thickness measurements, bioelectrical impedance, densitometry (underwater weighing), dual energy x-ray absorptiometry (DXA) and other methods^1,2,3. BMI can be considered a practical alternative to direct measures of body fat. A trained healthcare provider should perform appropriate health assessments to evaluate an individual’s health status and risks.